The present invention relates to a method for washing and sterilising a beer supply pipe employed in a beer supply system for delivering draught beer in a beer barrel to a beer dispenser tap or a beer pipe of a beer dispenser.
FIG. 1 shows a beer supply system for delivering draught beer from a beer barrel to a tap, generally installed in large pubs and beer halls.
In the system of FIG. 1, a refrigerator 200 for cooling draught beer to desired temperatures houses a draught beer barrel 201. An outlet 211 of the beer barrel 201 is equipped with a connector 202 having a CO2 gas inlet 221. A beer dispenser tap 203 is located in the hall or kitchen and connected to the connector 202 on the beer barrel 201 via a beer pipe 10 (e.g. vinyl tube). Further, a CO2 cylinder 204 is connected to the CO2 gas inlet 221 on the connector 202, so that the draught beer stored in the beer barrel 201 is delivered to the tap 203 under the gas pressure. The beer is poured into a mug or the like by operating the tap 203.
For the purpose of simplification, FIG. 1 depicts a single beer pipe extending from a beer barrel. In the actual beer supply system, a row of pipes are allocated on one beer barrel.
Recently, beer dispensers for cooling draught beer to desired temperatures are employed in relatively small-sized restaurants, etc. A typical beer dispenser comprises a cooler, a capillary cooling tube and a beer dispenser tap. Under the gas pressure from a CO2 cylinder, barrelled beer is delivered into the capillary cooling tube, where the beer is cooled.
In the beer pipes for delivering draught beer, the internal wall is contaminated with dregs or lees of beer (mainly consisting of proteins), bacteria/microorganisms, etc. Dregs of beer deteriorate the taste of the beer, and propagation of bacteria and microorganisms is unsanitary. Therefore, the beer pipes require regular cleaning. However, it is impossible to sufficiently wash out the beer dregs composed of a mass of proteins and bacteria/microorganisms, by simply washing the beer pipe with tap water.
Conventionally, cleaning of a beer pipe is conducted while the pubs, etc. are closed. The cleaning operation comprises withdrawing the beer from the beer pipe, filling the pipe with a cleaning material solution (washing solution) mainly comprising caustic soda (sodium hydroxide) or caustic potash (potassium hydroxide) or with a cleaning material solution (washing solution) mainly comprising caustic soda (sodium hydroxide) or caustic potash (potassium hydroxide) and further comprising hypochlorous acid soda (sodium hypochlorite), withdrawing the washing solution from the pipe after a predetermined time (e.g. 15 minutes to 8 hours), and washing the pipe with tap water. The filling and withdrawal of the cleaning solution may be repeated before the washing step. Where the cleaning solution mainly comprises caustic soda or caustic potash but contains no hypochlorous acid soda, sterilisation is effected by introducing an aqueous solution of hypochlorous acid soda (effective chlorine concentration: 200 to 500 ppm) into the pipe, after the pipe is washed with the use of the cleaning solution. The aqueous solution of hypochlorous acid soda has a bactericidal effect. The beer pipe of a beer dispenser is cleaned in a like manner.
However, this cleaning process has some defects due to the cleaning solution whose principal constituents are toxic chemicals such as caustic soda and caustic potash. For one, the washing step must be carried out carefully and completely so as not to leave any caustic soda or other toxic chemicals in the beer pipe, and such washing takes a substantial time.
Besides, the cleaning materials mainly comprising caustic soda, etc. are generally sold in the form of a plate-like or spherical tablet or liquid concentrate. Therefore, the cleaning solution needs to be prepared in a container by dissolving the tablet in water or diluting the liquid concentrate with water. A worker has the risk of hurting himself through physical contact with a highly concentrated toxic solution. Moreover, since the toxic chemicals like caustic soda still remain in the used cleaning solution, the cleaning solution cannot be left untreated. The beer-serving establishments must treat the used cleaning solution and discharge it in sewers on their own, or they need to commission waste treatment specialists for proper disposal.
It is an object of the present invention to provide a simple and safe method for washing and sterilising a beer supply pipe which delivers draught beer stored in a beer barrel to a beer tap, or a beer pipe of a beer dispenser.
According to the present invention, the method of washing and sterilising a beer supply pipe comprises a washing step of introducing strong alkaline electrolysed water into the beer supply pipe, and a sterilisation step of introducing strong acidic electrolysed water into the beer pipe, wherein both waters are produced by means of an electrolysed functional water generator.
The electrolysed functional water generator employed herein is a known apparatus which comprises an electrolytic cell including an anode, a cathode and a diaphragm provided between these electrodes. The electrolytic cell contains an aqueous electrolyte solution comprised of dissolved electrolytes such as sodium chloride (NaCl). The aqueous electrolyte solution is electrolysed by applying a DC voltage on the anode and the cathode, thereby generating strong alkaline electrolysed water and strong acidic electrolysed water.
This electrolysed functional water generator provides strong alkaline electrolysed water having a hydrogen ion concentration (pH) of 11.0 to 12.5 and an oxidation-reduction potential (ORP) of xe2x88x92650 mV or lower, and strong acidic electrolysed water having a hydrogen ion concentration (pH) of 1.5 to 3.0 and an oxidation-reduction potential (ORP) of +1100 mV or greater and containing hypochlorous acid with an effective chlorine concentration of 10 to 50 ppm. Note that the oxidation-reduction potential represents the oxidation capacity or reduction capacity of the solution.
The beer supply pipe washing/sterilisation method of the present invention ensures simple and effective removal of beer dregs deposited inside the beer pipe as well as extermination of bacteria and microorganisms.
Specifically, the electrolysed functional water generator electrolyses the aqueous electrolyte solution containing dissolved electrolytes such as sodium chloride (NaCl) to give strong alkaline electrolysed water and strong acidic electrolysed water. The former contains a trace of sodium hydroxide (NaOH) and hydroxide ions (OHxe2x88x92), which dissolve beer dregs by an action similar to soap. The latter contains a trace of hypochlorous acid (10 to 50 ppm), whose bactericidal effect can exterminate any bacteria or microorganisms.
In the strong alkaline electrolysed water for washing, the NaOH content is so limited that physical contact with the water is harmless to humans.
The hypochlorous acid contained in the strong acidic electrolysed water for sterilisation is decomposed and vanishes after being left in the air for a certain period or instantaneously on contact with an organic substance, thereby to turn the water harmless. In addition, reduction of the strong alkaline washing water can be accelerated by adding the strong acidic water, whereby the waters are neutralised to be as harmless as the pre-electrolysis water. Thus, the strong alkaline electrolysed water and strong acidic water used for washing and sterilisation can be discharged into sewers or the like without any special treatment.
In a preferable embodiment, the strong alkaline electrolysed water and the strong acidic electrolysed water are introduced into the beer pipe immediately after each water is produced in the electrolysed functional water generator. The reasons are given below.
Firstly, with respect to the strong alkaline electrolysed water, the water generated in the electrolysed functional water generator exhibits a higher dissolution property for proteins than caustic soda of the same pH value. This is presumably because of the correlation between the pH value and the oxidation-reduction potential (ORP), which is not greater than xe2x88x92650 mV in the case of the strong alkaline electrolysed water. Nevertheless, the strong alkaline electrolysed water is very unstable and prone to be oxidised (i.e. the absolute value of the ORP tends to decrease) Hence, for efficient dissolution of beer dregs (proteins), it is advantageous to utilise strong alkaline electrolysed water with a greater absolute ORP value, namely, just after it is generated.
Secondly, as mentioned above, the strong acidic electrolysed water generated in the electrolysed functional water generator has a hydrogen ion concentration (pH) of 1.5 to 3.0 and an oxidation-reduction potential (ORP) of +1100 mV or greater, and the water contains bactericidal hypochlorous acid. The combination of these factors enables a high sterilisation effect. As the time passes, however, the absolute ORP value decreases and the concentration of hypochlorous acid drops. Accordingly, for a higher sterilisation effect, it is preferable to use the freshest possible strong acidic electrolysed water.
In the above description, each electrolysed water is introduced directly from the electrolysed functional water generator into the beer pipe. Alternatively, the strong alkaline electrolysed water and the strong acidic electrolysed water may be temporarily reserved in separate tanks, from which either water is supplied into the beer pipe.
Specific modes of the washing/sterilisation treatment include a method comprising flowing strong alkaline or strong acidic electrolysed water through the beer pipe at a predetermined rate (e.g. 1.0 to 2.0 l/min), and a method comprising the steps of filling strong alkaline electrolysed water into the beer pipe, withdrawing the alkaline water from the pipe after a predetermined time (e.g. 5 to 30 minutes) and thereafter supplying strong acidic electrolysed water.
Further, the beer pipe washing/sterilisation method of the present invention may include a clearing step for removing strong acidic water which remains inside the beer pipe. For example, the clearing step may be carried out either by washing the inside of the beer pipe with tap water or by purging the beer pipe with carbon dioxide gas (CO2 gas), as a supplementary step following the sterilisation step of introducing strong acidic electrolysed water from the water generator into the beer pipe. Particularly, it is more effective for removal of the strong acidic electrolysed water to purge the beer pipe with CO2 gas and then to wash the inside thereof with tap water, following the sterilisation step of introducing strong acidic electrolysed water from the electrolysed functional water generator into the beer pipe.